This invention relates generally to a fiber optic sensor that includes a pair of multiple layer spiral-wound optical fiber coils on opposite sides of a flexural disk with the optical fiber coils being included in an interferometer. This invention particularly relates to sonar arrays suitable for mounting on a ship or submarine hull.
The present invention overcomes the deficiencies of the prior art in a low-cost assembly. This invention is directed to a fiber optic sensor that includes a flexural disk having a pair of fiber optic coils mounted on opposite sides thereof and optically coupled together to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The invention includes a housing having first and second end plates with a sidewall extending between the end plates. The sidewall has an inwardly facing groove in which an outer edge portion of the flexural disk is mounted. A compressive damper is mounted in the housing and arranged to exert a compressive force on the flexural disk to control movement thereof in response to acceleration of the flexural disk along a sensing axis and thereby control the output signal.
The compressive damper preferably comprises a pair of compressive damping members mounted between opposite sides of the flexural disk and the end plates.
The invention preferably further comprises a support member extending between oppositely facing portions of the first and second end plates. Each of the first and second compressive damping members preferably comprises a cylinder formed of a viscoelastic material such as Sorbothane(copyright)having a central passage therein with the first and second damping members being mounted in the housing such that the support member extends through the central passages in the first and second compressive damping members.
The end plates of the housing preferably have ribbed inner surfaces arranged so that a plurality of ribs extends away from the end plates inward toward the first and second compressive damping members with the first and second compressive damping members being compressed between the ribs of the opposite end plates. The ribs preferably are arranged to extend radially between the support member and the sidewall of the housing. An adjacent pair of the ribs in one of the end plates preferably has slots formed therein for mounting an optical coupler in the housing.
The housing preferably comprises a plurality of routing tabs extending inward from the sidewall for retaining optical fibers in selected positions in the housing.
The flexural disk includes a central passage therethrough and the invention preferably includes a central support extending through the central passage in the flexural disk with an inner edge of the central passage in the flexural disk being spaced apart from the support member. The invention may further comprise a shear damper mounted on the central support member and arranged to exert a radial force on the inner edge of the flexural disk to dampen vibrations of the flexural member and thereby further control the output signal amplitude. The shear damper preferably comprises a length of tubing formed of a viscoelastic material such as nitrile, polyurethane or silicone rubber. The central support preferably includes a circumferential slot in which the shear damper is mounted.